The Characteristics of hydrogen solution in Fe-Cr-Ni austenitic alloys investigated by first-principles calculation; The Roles of Cr and Ni atoms on average and local hydrogen concentration

Moriyama, Junichiro*; Takakuwa, Osamu*; Yamaguchi, Masatake   ; Ogawa, Yuhei*; Tsuzaki, Kaneaki*

In some austenitic stainless steels (Fe-Cr-Ni basic composition), hydrogen exhibits a high solution strengthening capacity with increasing solid solution hydrogen concentration that is difficult to explain by dimensional effects. In order to understand this phenomenon, it is necessary to understand the local hydrogen concentration in addition to the average solid solution hydrogen concentration in the Fe-Cr-Ni system. Since the average solid solution hydrogen concentration depends on the amount of Cr and Ni, the interaction between these substitutional atoms and hydrogen atoms is considered to be an important factor to focus on. In this study, first-principles calculations were used to quantify the interaction between Cr and Ni atoms and hydrogen atoms, and to evaluate the average solid-solution hydrogen concentration (occupancy) and its effect on the distribution.